You mean of course what I'd call trousers...
Not sure what hawks you get in Pennsylvania, but quite a few different ones have the "trousered" look.
Falcons are a group of related hawks. Ones you may know include peregrine and (American) kestrel. They have fast, agile flight, and long, sharply pointed wings (triangular points, without "finger" feathers).
Could also be what we in UK'd call a buzzard -- these include your red-tailed hawk. They have broad wings with finger-feathers.
The other type you might see is like our sparrowhawk. Sharp-shinned hawk is I think your main one of these. Long tail, short, rounded wings, dashing, flickering flight with frequent glides. (I think American kestrel is also called sparrowhawk sometimes).
There, that's exhausted my knowledge of American hawks...
Good luck!